After that, subjects will then be required to go to the endocrinology clinic at TTSH for control of their hyperthyroidism via ATD. This may take about 6 months to attain stable thyroid hormones levels (FT4, FT3, TSH). Subjects will be followed up every 6-8 weeks as per standard medical practice by theTTSH endocrinologist and have their ATD doses adjusted till their thyroid function tests are stable`. When this happens, subjects will continue with the remaining part of the research, which is Study Visit 3. With the exception an additional urine pregnancy test, Study Visit 3 is exactly the same as Study Visit 2.